Navigation devices that require a data medium, e.g., a compact disc or a DVD (digital versatile disc), in order to perform navigation are already known. A digital map containing a road system is placed on the data medium, the navigation device regularly accessing the data medium to calculate the trip route and to output driving instructions. The expensive data-media drive is thus available in the vehicle only for the navigation device, or the drive cannot be used for other data media while vehicle navigation is being carried out. Navigation methods in which a navigation device in the vehicle accesses an external database without requiring a data medium in the vehicle are also known. However, additional costs are thereby incurred for data transfer.